Refrigerator defroster



Jan. 16, 1951 c. s REv 2,538,660

REFRIGERATOR DEFROSTER Filed June 30, 1947 2 Sheets-Sheet 1 v \NVENTOBGLJFFORD ScHRava A 116 RNEYS Jan. 16, 1951 c, s v 2,538,660

REFRIGERATOR DEFROSTER Filed June 30, 1947 2 Sheets-Sheet 2 2 viii faA110 RN xs Patented Jan. 16,1951

UNITED STATES PATENT OFFICE REFRIGERATOR DEFROSTER Clifford B. Shreve,Buchanan, Mlch., assignor to Tyler Fixture Corporation, Niles, -Mich., acorporaticn of Michigan Application June 30, 1947, Serial No. 758,162

3 Claims. 1

This invention is concerned with refrigeration, and more particularly,with a refrigerating construction which is particularly adaptable toopen display frozen food cabinets, to maintain the merchandise thereinat a desired low temperature, while readily accessible to the customerwho may select and serve himself from the articles of merchandise whichare kept at a desired low temperature in an open display compartment.

With my invention, the evaporator coils of the refrigerationconstruction are located remotely from the merchandise displaycompartment, and the air from the display compartment is picked up andfirst carried through the evaporator where its moisture will condenseand be deposited. Thus the cooled air, before being discharged tocontact the merchandise, is first dried, that is, has the major portionof its water vapor removed therefrom.

One major object of the present invention is to provide a novelstructure and apparatus for defrosting the evaporator coils on which thecondensed moisture collects. Preferably, and also forming a part of myinvention, two evaporators are used, which are alternately defrosted. Ineach of these evaporators there is the usual and normal refrigeratingevaporating coil, together with which is a second coil, which may be ofsimilar structure, through which a defrosting fluid of relatively hightemperature is pumped and rapidly circulated for quickly and efficientlydefrosting the evaporators and adjacent parts upon which frozen moisturehas been deposited.

Many other objects and purposes, and novel structure for the attainmentthereof, will ap-,-

pear and be understood from the disclosure of the invention, describedin the following description, and illustrated in the accompanyingdrawings, in which:

Fig. 1 is a vertical section through a cabinet with which my inventionis used, and showing a structural embodiment of my invention,

Fig. 2 is a fragmentary transverse vertical section toward one side andthrough the upper end portion of the display cabinet,

Fig. 3 is an enlarged vertical section of the valves and their operatingmechanisms used for controlling the refrigerant and the defrosting fluidflows, and

Fig. 4 is an enlarged horizontal section through the reversible pumpused for pumping the warm defrosting fluid.

Like reference characters refer to like parts in the different figuresof the drawings.

The cabinet in Fig. 1 has a bottom I and in 2 practice. though theinvention is not limited solely thereto, is of the open display type orcharacter, similar to that shown in Design Letters Patent #140,198,issued upon the application of Jerry Tyler, January 30, 1945. In thelower part, and projecting forward from the upper part, there is amerchandise holding compartment, which is open at its top for access bya customer at the front when selecting the merchandise which is to bepurchased. The vertical ends 2 of the cabinet, also at the vertical backand at the front upper part of the cabinet, are joined with horizontal,relatively narrow, top sections 3, from the inner edge portions of whichvertical walls 4 extend downwardly, providing a well in which a part ofthe refrigerator mechanism used is located.

The evaporator coils 6 and 60 are located in the upper portions of thespaces between the ends 2 and the walls 4, inwardly thereof, as shownin- Fig. 1. Vertical partitions 5 extend from the evaporators to thebottom of the cabinet, which at their lower portions have openings inwhich motor driven fans I are positioned. The merchandise racks 8 arelocated in the lower part of the cabinet, below the open upper side ofthe forwardly extending lower cabinet section. The two evaporator coils6 and 60, two series of which are used, as shown, are substantiallyidentical in structure (Fig. 2). Through the evaporator coils 6 therefrigerant fluid is circulated. The warm defrostingfiuid is circulatedthrough the coils 60, as hereafter described.

The compressor 9 of the refrigerating system is located in the describedwell and suitably supported, the refrigerant fluid being conductedthereto through a branch pipe I0 connected with a pipe II, whichconnects at opposite ends with the outlet ends of the two refrigerantevaporator coils 6. The compressor forces the refrigerant fluid outthrough an outlet pipe 12 and thence through a coil l3, which isinterposed in the length of the pipe l2, to the condenser l4, therefrigerant being delivered to a tank I! around which the coils l3 arewound, as shown.

The refrigerant goes from the tank 15 through a connecting pipe I6 (Fig.3) to a valve housing I! which has two outlet lead pipes l8 connectedtherewith.

The valves in housing I! and their operations in connection with thehousing will be hereinafter described. When the valves are open, asshown 'in Fig. 3, the refrigerant passing through the pipe IE will gothrough both of the outlet pipes It to automatic temperature controlledvalves at It,

one for each outlet pipe, which at all times supply the correct amountof refrigerant to the evaporators. The refrigerating fluid passes fromthe valves at l9 through pipes to the entrance ends of the evaporatorcoils 6. The structure described is substantially standard in essentialsin the usual refrigerating systems, except that the valves shown withinthe valve housing H, in Fig. 3 are not used, but there is a direct opencommunication from a pipe at Hi to the outlet pipe or pipes at i8without any intervening valve with my invention, such rapid defrostingis attained.

Above the bottom of the well, a receptacle 2| is positioned withinwhich, in the disclosure, a liquid 22 is held. The coil i3 is submergedin the liquid and also the tank. If: is partly submerged. 1.

Heat from the refrigerating fluid passing through the coil I3 is givenoff to the liquid, also heat from such fluid in the tank [5 raises thetemperature of the liquid 22.

A gear pump 23 (Figs. 4 and l) is submerged in the liquid 22 havinginlet ports, for the liquid to come to the gears. The pump is driven byan electric motor 24. Two outlet pipes 25, with suitable check valves25a therein, lead from the tank 2| to the entrance ends of the twodefrosting coils 60. From the outlet ends of the defrosting coils, pipes26 return the liquid to the tank. The motor 24 is a reversible motor. Inone direction of turning it circulates the defrosting liquid through oneof the defrosting coils 60. Upon reversal it circulates the liquidthrough the other defrosting coil. The check valves 25a preventcirculation through the defrosting coil to which the liquid is notdirectly pumped.

The water from the melted frost which has deposited on the evaporatorcoils 6, upon defrosting, is caught by pan-like members 21 and drainedthrough pipes 28 into the well mentioned. the lower side of which isshown as a an 28a in Fig. 1. side the cabinet.

As shown in Fig. 3, the valve housing H has two valves 29 which mayclose openin s between the inlet pipe l6 and the outlets i8 when movedto upper positions. With each of said valves an armature 30 isconnected, which is moved upwardly on passing an electric currentthrough a solenoid winding 3|, one associated with each of thearmatures. The electric circuits leading to the two solenoid windingsare independent circuits and each is adapted to be clos d or opened by asuitable switch. The motor 24 is likewise controlled as to its startingand direction of turning by suitable manually or automaticallycontrolled switch means for the purpose. The fans I also have theirdriving motors each in an independent circuit so that each may beindependently controlled. The fans 7 when operating draw cold airdownwardly outside of the vertical partitions 5 and deliver it below themerchandise From the pan it may be drained to outi:

holding racks 8, the air circulating upwardly between the walls 4 of thewell and said partitions, and thus over the refrigerating and defrost ncoils. Warm air entering from the outside in front of the reflector ormirror 32, which is mounted below th bottom of the well, first mustcirculate around and through the coils 6 and 80 and will have its watervapor condensed and deposited on the coils.

It is apparent that the accumulation of frost 0n the evaporator anddefrosting coils may be relatively rapid, and that a frequent defrostingshould take place.

In the operation, one of the refrigerating coils is continued inoperation while the other is defrosted. The solenoid winding 3| forlifting one of the valves 29 is energized by closing its solenoidwinding circuit, whereupon the circulation of the refrigerant fluid toone of the refrigerating coils B is stopped. For example, if the valve29 at the right in Fig. 3 was lifted to close the opening above it,refrigerating fluid would thereupon pass from the inlet pipe I 6 outwardonly through the outlet pipe |8 at the left. After the selected valve 29has been moved to closed position, the motor 24 is started in the properdirection of rotation to pump warm liquid 22 from the tank 2| throughthe defrosting coil 60 whic is associatedwith and in close proximity tothe refrigerating coil 15, the circulation of refrigerant fluid throughwhich has been cut off. The warm liquid 22 circulated rapidly throughthe selected defrosting coil 60, gives off heat which melts the frostdeposit on the refrigerant coil which, for the time, has norefrigerating iiuid passing through it.

When a coil at one side has been defrosted. the closed valve 29 isreleased to move to its nor mal lower position, and the other valve 29lifted by closing the circuit of its associated winding 3|. This cutsoff th refrigerating fluid from the coil 8, which has been operatingwhile the defrosting of the other coil 6 took place. The motor isreversed, and the same circulation of the warm defrosting liquid throughthe other defrosting coil 60 occurs.

Of course, it is tobe understood that if one end of the display case inwhich the apparatus is installed should be more subject than the otherto the accumulation of deposited frost on its refrigerating coil, it canbe more frequenly defrosted than the other, and there is no necessity ofdefrosting one refrigerating coil immediately after the other. Each isindependently controlled as to its time of defrosting.

Defrosting may be done at any time during the day while the cabinet isopen at the front and in use, with a continuous maintenance of themerchandise at a desired low temperature. If the defrosting liquidshould be pumped through a defrosting coil 60 without closing one or theother of the valves 29, through inadvertence in operation, no damagewould occur beyond a loss of refrigeration. But in the best operation,and the one which should be used, a valve 29 should be closed to stoprefrigerant circulation to the evaporator coil 6 which is beingdefrosted, and the warm defrosting fluid pumped through its associateddefrosting coil 60, while the other refrigerating coi1 continues innormal functional operation.

The invention is defined in the appended claims and is to be consideredcomprehensive of all 1. In a structure as described, a merchandiseholding cabinet having a portion of the space' therein adapted tocontain merchandise, said merchandise holding portion being in the lowerp rt of the cabinet, a, mechanical refrigeration system including, acompressor, condenser, and two evaporators spaced from each other, eachremote from the merchandise holding portion, with pipes for carrying afluid refrigerant from the compressor through the condenser and to saidevaporators and'thence back to the compressor, means for circulating airto and over said evaporators, thence to the lower merchandise holdingportion and back to the evaporators, valve control means between thecondenser and said evaporators in the conduit leading to the evaporatorsselectively operable to stop fluid refrigerant circulation to a selectedevaporator and continue such circulation to the other evaporator, a,fluid holding receptacle, a pump therein, means to drive the pump, twoconduits leading from the pump to said evaporators and back to thereceptacle, said conduits at each evaporator having portions in closeheat-exchange proximity to the evaporators, and means for controllingthe pump operation to pump the fluid in said receptacle selectivelythrough one only of said conduits leading from said pump.

2. A structure as defined in claim 1, the pipe connecting the compressorand condenser in-- cluding a coil, and said fluid in said receptaclecomprising a liquid in which the coil is submerged to raise thetemperature of the liquid.

3. A structure as defined in claim 1, said means for driving andcontrolling the pump operation comprising a reversible electric motor.

CLIFFORD B. SHRE'V'E.

